If you are leaning over to unbolt a gate, how long does that take? A few seconds? Yes annoying I know, but come on a few seconds to get your full price. Solutions, 1) give your customers a timetable for their cleans, but this will leave you with really strict schedules and no le-way for hold ups. 2) a quick call the day before works well. If you really would have 50 people to call on one day. I really would suggest the timetable!